Vibrating Plate with Individually Adjustable Vibration Generators

ABSTRACT

A vibrating plate comprises an upper mass with a drive, a lower mass with a soil contact plate ( 12 ), and a vibration generator device, which belongs to the lower mass and which acts upon the soil contact plate ( 12 ). The vibration generator device comprises at least two individual exciters ( 13 ) each having an unbalanced shaft ( 2 ). The individual exciters ( 13 ) can be individually controlled with regard to the rotational speed and/or phase position of the respectively assigned unbalanced shaft ( 2 ). A mechanical coupling of the unbalanced shafts ( 2 ) is thus unnecessary. The unbalanced shaft ( 2 ) of an individual exciter ( 3 ) can be rotationally driven by a hydraulic motor ( 4 ). The position of the unbalanced shaft ( 2 ) is determined in at least one position by a position indicator ( 7 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vibrating plate according to thepreamble of patent claim 1.

2. Description of the Related Art

Vibrating plates are known and are made up in principle of a lower masshaving a soil contact plate and an upper mass that is flexibly coupledto the lower mass so as to be movable and that has a drive (e.g. aninternal combustion engine or an electric motor). The drive drives avibration exciter device that appertains to the lower mass and thatcharges the soil contact plate.

As a vibration exciter device, what is known as a one-shaft exciter orplate compactor is known in which the drive rotationally drives animbalance shaft that bears an imbalance mass. During its rotation, theimbalance shaft pulls the soil contact plate upward and forward in orderto achieve a forward movement. Subsequently, the soil contact plate ispressed downward by the action of the imbalance shaft and strikes thesoil that is to be compacted.

In larger vibrating plates, the vibration exciter device has two orthree imbalance shafts that are coupled to one another mechanically, orwith a positive fit. In the two-shaft exciter, two imbalance shafts,each bearing an imbalance mass, are positively coupled to one anotherand are situated so as to be capable of rotation in opposite directions.The phase relation of the imbalance shafts to one another can beadjusted mechanically using a linkage device or a differential gearmechanism. As drives for the adjustment, hydraulic cylinders, Bowdencables, or spindles are known. By adjusting the phase position of theimbalance shafts to one another, the direction of a resultant forcevector can be modified, resulting in a modification in the advancebehavior. In particular, in this way forward and backward travel of thevibrating plate can be achieved.

In another development, the imbalance mass on one of the imbalanceshafts is divided into two or more partial imbalance masses that can beadjusted relative to one another. If the partial imbalance masses on theimbalance shaft are adjusted asymmetrically to one another, a yaw momentabout the vertical axis of the vibration exciter device can be produced,enabling the vibrating plate to be steered. Given a symmetricaladjustment, in particular if partial imbalance masses are fixedlyattached to the relevant imbalance shaft and other partial imbalancemasses are capable of being moved relative thereto, the resultingimbalance effect can be adjusted, enabling setting of the resultantimbalance forces.

Due to the strong imbalance effect, the forces on the adjusting drivesfor adjusting the phase position of the imbalance shafts to one anotherand the phase position of the various imbalance masses on one imbalanceshaft are high. The adjustment mechanism is exposed to high alternatingforces, which have an adverse effect on its working life span.

Standardly, the imbalance shafts in known vibration exciter devices aresituated parallel to one another. In modern vibrating plates, this makesit possible to achieve forward and backward travel, as well as rotatingthe vibrating plate in place or causing it to travel on a curved path.In some applications, however, the user will desire a lateral movementof the vibrating plate, for example in order to be able to drive behindlateral projections. When compacting soil on laterally inclinedsurfaces, the vibrating plate often drifts obliquely downward, so thatthe operator has to orient the vibrating plate obliquely in order tocompensate this. However, this means that at the upper and lower edgethe soil is compacted only by a corner of the soil contact plate,resulting in unsatisfactory compaction.

In such cases, it would be helpful for the vibrating plate to be, ableto execute a lateral movement. In order to achieve such a lateralmovement, however, the vibration exciter device would have to achieve acorresponding force effect in the lateral direction, which is possibleonly using imbalance shafts that are situated obliquely or at an angle.The angled situation of imbalance shafts in known vibration exciterdevices, and their mechanical coupling to the overall drive mechanism,would require a significant gearing expense, with correspondingly highcosts and weight.

OBJECT OF THE INVENTION

The underlying object of the present invention is to indicate avibrating plate in which the mechanical outlay for the drive of theimbalance shafts in the vibration exciter device can be reduced.

According to the present invention, this object is achieved by avibrating plate according to patent claim 1. Advantageous furtherdevelopments of the present invention are indicated in the dependentpatent claims.

A vibrating plate according to the present invention has an upper masscomprising a drive, a lower mass comprising at least one soil contactplate, and a vibration exciter device that charges the soil contactplate. The vibration exciter device has at least two individualexciters, each comprising at least one imbalance shaft that bears animbalance mass. According to the present invention, the individualexciters can be individually controlled with respect to the rotationalspeed and/or phase position of the respectively allocated imbalanceshaft.

Thus, according to the present invention small units in the form ofindividual exciters are provided that in the simplest case have only asingle imbalance shaft. The rotational speed and the phase position ofthis imbalance shaft can be controlled individually, i.e. independent ofthe rotational speed or the phase position of other imbalance shafts.The overall vibration exciter device, in contrast, has at least two ofthese individually controllable individual exciters.

The phase position of the imbalance shaft relates to its position inrelation to the other imbalance shaft or shafts that work together withit. If one of the imbalance shafts is defined as a reference system, theother imbalance shaft or shafts can either rotate with the same phaseposition or can be rotated by a particular phase angle thereto. Thephase position of each of the imbalance shafts should be defined withreference to a unified reference system.

In a particularly advantageous specific embodiment of the presentinvention, each of the individual exciters has a hydraulic motor orelectric motor that rotationally drives the respective imbalance shaft,and has a position sensor that acquires the position of the imbalanceshaft in at least one position. In this way, on the one hand each of theimbalance shafts can be individually driven by the hydraulic motor(electric motor) allocated to it, while on the other hand via theposition sensor the actual position of the imbalance shaft is regularlyor constantly monitored. The position sensor should acquire the positionof the imbalance shaft at least in one position, i.e. once during arotation of the imbalance shaft, from which the rotational speed of theimbalance shaft can be determined and intermediate positions can also beinterpolated. Of course, the position sensor can also be constructed insuch a way that it permanently acquires the rotational position of theimbalance shaft and thus its rotational speed. The precise recognitionof the rotational position is important in order to enable the phaseposition of the imbalance shaft to be derived therefrom.

Advantageously, an actuating element, in particular a hydraulic valve,is allocated to the hydraulic motor, the individual exciter having acontroller for evaluating a signal from the position sensor and forcontrolling the actuating element, in such a way that a targetrotational speed and/or target phase position that are prespecified tothe controller for the relevant imbalance shaft is achieved.

Instead of the hydraulic motor, another suitable individual drive can beused for the individual imbalance shafts of the individual exciters,e.g. a controllable electric motor. However, at present electric motorsare still too susceptible to vibration, and therefore, due to the strongvibrations, will probably not have a sufficient life span.

Thus, each individual exciter has its own control circuit in which theimbalance shaft forms the control path and the position sensor forms themeasurement element. The position of the imbalance shaft, and thus itsactual phase position and actual rotational speed, is determined withthe aid of the position sensor and is supplied to the controller as ameasurement value. Of course, the evaluation of the signal by theposition sensor can also first take place in the controller itself, inorder for example to determine the actual rotational speed. On the basisof the values specified to the controller for the target rotationalspeed or the target phase position, the controller controls theactuating element, in particular the hydraulic valve, so that theallocated hydraulic motor drives the imbalance shaft in the desiredmanner.

In a particularly advantageous specific embodiment of the presentinvention, a central control unit is provided in order to coordinate thecontroller of the individual exciters and in order to specify anindividual target rotational speed and/or target phase position for eachcontroller of the individual exciters, in such a way that the soilcontact plate behaves in a way that is desired by an operator and/or isspecified by an operating or driving program.

The central control unit, e.g. a process computer, thus has the task offorming the connecting element between the operator and the individualexciters of the vibration exciter device. The operator gives the centralcontrol unit a desired driving instruction for the vibrating plate, e.g.forward, backward, rotating, lateral, or curved travel. In the centralcontrol unit, corresponding driving programs are allocated to this wishon the part of the operator, from which specifications are derived forthe individual target rotational speeds, and in particular target phasepositions, of the imbalance shafts in the individual exciters. Thesetarget values are individually supplied to the controllers of theindividual exciters, and the controllers of the individual excitersensure a corresponding behavior of the respectively allocated imbalanceshafts.

In another specific embodiment of the present invention, instead of thecontrollers of the individual exciters and the higher-order centralcontrol unit, only a “generally responsible” central controller isprovided. The central controller is used to evaluate the signals fromthe individual position sensors of the individual exciters and for theindividual controlling of the actuating elements of the individualexciters in such a way that the behavior of the soil contact platedesired by the operator and/or specified by a driving program isachieved. In contrast to the decentralized design described above, thecentral controller provides a centralized controlling. The centralcontroller centrally acquires the behavior of each imbalance shaft andtakes the measures required for the imbalance shaft to carry out therotational behavior demanded of it. Here as well, the decisive factor isthe operator's wishes, or a prespecified driving program, according towhich e.g. forward travel or backward travel of the soil contact plateis demanded.

In the controlling of the rotational speed and phase position of theimbalance shafts, it is possible to exploit a particular feature: due toenergetic interaction effects, imbalance shafts situated on a commonrigid bearer have the tendency to synchronize with one another withrespect to their rotational speed. Presupposing corresponding targetvalues in particular for the phase position, the controllers then onlyhave to adjust the changes or differences out of the self-synchronizingposition in order to achieve the desired relative position or phaseposition of the relevant imbalance shaft.

Preferably, the imbalance shafts of the individual exciters are drivenwith the same rotational speed. In this way, a behavior of thecooperating individual exciters can be achieved that corresponds to thebehavior of known purely mechanically operating vibration exciters, inparticular those based on a positive coupling of the participatingimbalance shafts.

However, advantageously, the individual controllability of theindividual exciters also makes it possible for the imbalance shaft to bedriven by at least one of the individual exciters with a differentrotational speed than the imbalance shafts of the other individualexciters. In particular, this different rotational speed can be anodd-numbered multiple, e.g. three times or five times, of the rotationalspeed of the imbalance shafts of the other individual exciters. In thisway, in particular applications a particular vibration behavior of thevibration exciter device can be achieved that would be practicallyimpossible to realize, or realizable only at significant expense, inpurely mechanically operating vibration exciters having toothed gearmechanisms. An only temporary deviation of the rotational speed would bealmost completely excluded in purely mechanically operating vibrationexciters, because for this purpose a manual transmission would berequired.

The different rotational speed of at least one of the imbalance shaftscan make it possible to apply particularly hard impacts to the soil forparticular cases of application.

In a particularly advantageous further development of the presentinvention, at least one of the individual exciters is capable of beingcontrolled in such a way that the imbalance shaft allocated to itintentionally achieves a non-uniform rotational speed. In principle, itmust be assumed that the rotational speed of an imbalance shaftfluctuates due to the permanent exchange of energy between the kineticenergy of the imbalance shaft itself and the soil contact plate chargedby it. The allocated controller will always attempt to keep therotational speed of the imbalance shaft at the prespecified targetvalue. However, due to the high speed it must be assumed that thecontroller will not be able to compensate rotational speed fluctuationsfor the exchange of energy. Rather, in the normal case it will besufficient to set the average phase position and rotational speed of theimbalance shaft to the desired target value.

However, in the specific embodiment named here, the controller has thetask of intentionally impressing a non-uniform rotational speedindependent of the rotational speed fluctuation that is almostunavoidable in practice. Here it can be useful if, during a rotation,the imbalance shaft intentionally achieves different rotational speedsin order e.g. to enable a longer contact with the soil of the soilcontact plate, so that the impact energy can be effectively transmittedinto the soil.

In a particularly advantageous specific embodiment of the presentinvention, a second vibration exciter device that charges the soilcontact plate is provided, having at least two imbalance shafts that arepositively coupled to one another and that are driven so as to rotate inopposite directions. A position sensor is allocated to at least one ofthe imbalance shafts of the second vibration exciter device in order todetermine the phase position of this imbalance shaft. A signal from thisposition sensor is supplied to the central control unit or to thecentral controller in order to coordinate the rotational speed and/orthe phase position of the imbalance shafts of the second vibrationexciter device with the individual exciters.

In this specific embodiment, a “conventional” vibration exciter devicethat operates purely mechanically through positive coupling (toothedgears) is thus combined with the above-described individual exciters ofthe vibration exciter device according to the present invention. Thismakes it possible to continue to use the purely mechanically operatingsecond vibration exciter device, whose principle of operation has provedvery successful over many years. For example, the second vibrationexciter device can be used to produce vibration forces that are usedonly for forward or backward travel, while force effects for steering orfor lateral travel of the vibrating plate are achieved by the vibrationexciter device with individual exciters according to the presentinvention. In another variant, the purely mechanically operating secondvibration exciter device is used exclusively to produce verticalcompaction forces, while the forces for advancing and steering thevibrating plate are achieved by the individual exciters of the vibrationexciter device according to the present invention.

The central control unit or central controller coordinate the behaviorof the second vibration exciter device with the individual exciters ofthe vibration exciter device according to the present invention in orderto achieve the desired behavior of the soil contact plate.

Preferably, the position sensor has a device for acquiring the angle ofrotation. This makes it possible to precisely acquire the position, andthus also the rotational speed, of an imbalance shaft at all times.

In another specific embodiment of the present invention, the individualexciters and/or the second vibration exciter device are situated so asto be distributed on a plurality of soil contact plates. Thus, the lowermass has a plurality of soil contact plates to each of which, a purelymechanical second vibration exciter device and/or one or more individualexciters are allocated. Here, almost arbitrary combinations arepossible. Of course it is also conceivable to distribute only individualexciters of the vibration exciter device according to the presentinvention on the soil contact plates, without requiring the presence ofa second vibration exciter device.

In a particularly advantageous specific embodiment of the presentinvention, at least some of the imbalance shafts of the individualexciters are situated on the soil contact plate in such a way that theforce vectors produced by them act in different planes. Through therotation of the imbalance shafts, the imbalance masses situated thereoneach produce a centrifugal force vector that rotates in a plane that isperpendicular to the axis of rotation of the imbalance shaft. If theaxes of rotation of the imbalance shafts are situated so as to bedifferently oriented on the soil contact plate, the force vectors of theimbalance masses correspondingly also act in different planes. Dependingon the controlling of the imbalance shafts, force effects in differentdirections can be produced that bring about a corresponding movementbehavior of the soil contact plate.

Preferably, at least some of the imbalance shafts of the individualexciters are situated on the soil contact plate in a star shape,axially, parallel, or at angles to one another. Of course, any mixedcombinations of these types of arrangements are also conceivable inorder to achieve a desired travel and directional behavior of the onesoil contact plate or the plurality of soil contact plates.

In a further development of the present invention, at least one of theimbalance shafts bears a larger imbalance mass than do other imbalanceshafts. Such a specific embodiment takes into account for example therecognition that in the large majority of cases the vibrating plate isused in forward and backward travel operation, while rotations, as wellas curved and oblique travel, represent exceptions or require smallerforce effects. Correspondingly, the individual exciters that are usedfor forward and backward travel should have imbalance shafts having alarger imbalance mass than do the individual exciters that are used onlyto bring about curved or oblique travel.

These and additional advantages and features of the present inventionare explained in more detail below with the aid of the accompanyingFigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic section through an individual exciter accordingto the present invention;

FIG. 2 shows a vibration exciter device according to the presentinvention having two individual exciters;

FIG. 3 shows a variant of a vibration exciter device according to thepresent invention having two individual exciters;

FIG. 4 shows a top view of a soil contact plate having a vibrationexciter device according to the present invention, according to a firstspecific embodiment of the present invention;

FIG. 5 shows a top view of a soil contact plate having a vibrationexciter device according to the present invention, according to a secondspecific embodiment of the present invention;

FIG. 6 shows a top view of a soil contact plate having a vibrationexciter device according to the present invention, according to a thirdspecific embodiment of the present invention;

FIG. 7 shows examples of arrangements of individual exciters.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As described above, the present invention relates to a soil compactiondevice realized as a vibrating plate, whose design is known inprinciple. An essential component of a vibrating plate is a vibrationexciter device that introduces a directed vibration into a soil contactplate. The vibrating soil contact plate acts on the soil in order tocompact it. In addition, the resultant overall force produced by thevibration exciter device can bring about travel in the longitudinal orlateral direction and a steering of the vibrating plate. Because thisdesign has long been known, a more detailed description is not necessaryhere.

The vibrating plate according to the present invention has a vibrationexciter device having at least two individual exciters 13 that act on asoil contact plate 12.

FIG. 1 shows a sectional representation of the schematic design of anindividual exciter 13 according to the present invention.

In an e.g. tube-shaped housing 1, an imbalance shaft 2 is mounted so asto be capable of rotation. Imbalance shaft 2 bears an imbalance mass 3.

Imbalance shaft 2 is rotationally driven by a hydraulic motor 4.Hydraulic fluid is supplied to hydraulic motor 4 via a hydraulic line 5,by a hydraulic supply system (not shown). The hydraulic supply systemcan be situated essentially on the upper mass of the vibrating plate. Acomponent of the hydraulic supply system is for example a diesel,gasoline, or electric aggregate that drives a hydraulic pump.

The hydraulic pump produces a hydraulic pressure in a hydraulic fluidthat can be stored in a hydraulic storage device. Furthermore, ahydraulic supply container for collecting and storing the hydraulicfluid must be present. Due to the strong vibrations in the lower mass,it is useful if most of the components of the hydraulic supply systemare situated in the upper mass, which is decoupled in terms of vibrationfrom the lower mass. In this way, it is necessary only to create aconnection from the hydraulic supply system to the hydraulic motor 4with the aid of hydraulic line 5.

Downstream from hydraulic motor 4 there is situated a hydraulic valve 6that acts as an actuating element that controls the hydraulic outflowafter hydraulic motor 4, and thus influences the rotational speed ofhydraulic motor 4. Of course, hydraulic valve 6 can also be situatedupstream from hydraulic motor 4.

At an end of imbalance shaft 2 situated opposite hydraulic motor 4,there is situated a position sensor 7. Position sensor 7 (e.g. a devicefor acquiring the angle of rotation) is able to acquire the position ofimbalance shaft 2 in at least one position. This can take place forexample optically, magnetically, inductively, or capacitively. From thepossibility of acquiring the position of imbalance shaft 2 at least onetime during a rotation thereof, the rotational speed and the phaseposition of imbalance shaft 2 can be determined. In addition, it isstraightforwardly possible to determine the position of the imbalanceshaft 2 with sufficient precision at any time using interpolation overtime. The position of imbalance shaft 2 is important because imbalancemass 3 carried by it produces a strong centrifugal force effect duringrotation. The centrifugal force of imbalance mass 3 works together withthe centrifugal forces of the other individual exciters 13 that belongto the vibration exciter device, thus producing an overall resultantforce effect that determines the movement behavior of soil contact plate12 charged by individual exciters 13. Soil contact plate 12 can move inthe desired manner only when both the rotational speeds of imbalanceshafts 2 and also their phase positions are precisely coordinated to oneanother.

The vibration exciter device according to the present invention has atleast two of these individual exciters 13 that are situated on soilcontact plate 12 in a suitable manner. Possible specific embodiments aredescribed below.

Individual exciter 13 shown in FIG. 1 also has a controller 8 thatevaluates the signal produced by position sensor 7 and determines atleast the rotational speed and/or the position of imbalance mass 3relative to a particular in time (phase position).

In addition, controller 8 also receives (as is explained below) a targetvalue signal 9 that specifies the required target rotational speed ortarget phase position. Controller 8 correspondingly controls hydraulicvalve 6 in order to achieve the desired rotational speed and phaseposition of imbalance shaft 2 or imbalance shaft 3, with the aid ofhydraulic motor 4.

FIG. 2 shows the schematic design of the vibration exciter deviceaccording to the present invention having two individual exciters 13according to FIG. 1. In FIG. 2, individual exciters 13 are situatedparallel to one another.

A central control device 10 is provided that specifies target valuesignals 9 for each of the controllers 8 of individual exciters 13. Eachcontroller 8 then ensures in the manner described above, for theindividual exciter 13 allocated to it, that imbalance shaft 2 behaves inthe desired manner.

Target value signals 9 specified by central control device 10 can differfor each of individual exciters 13. Essential distinguishing parametersinclude target rotational speed, target phase position, and targetdirection of rotation. The change of the direction of rotation isoptional and requires an additional constructive expense in therealization of hydraulic motor 4 or of hydraulic valve 6. In the normalcase, a change in the direction of rotation will not be required.

As examples, FIG. 2 shows two individual exciters 13. Of course, it isstraightforwardly possible to provide a vibration exciter deviceaccording to the present invention with more than two individuallycontrollable individual exciters 13.

FIG. 3 shows another specific embodiment of the present invention, inwhich the vibration exciter device is also shown with two individualexciters 13.

Differing from the individual exciters described in connection withFIGS. 1 and 2, the individual exciters in FIG. 3 do not haveindividually allocated controllers 8. Rather, the signals from positionsensor 7 are supplied to a central controller 11 that evaluates all thesignals from all the individual exciters 13. Central controller 11 thencorrespondingly controls each of the hydraulic valves 6 individually, inorder to achieve the desired behavior of imbalance shaft 2 individuallyfor each exciter 13.

In this specific embodiment, the constructive expense is lower than inthe specific embodiment shown in FIGS. 1 and 2, due to the fact thatonly a single controller is required. This in turn offers the advantagethat the individually allocated controller 8 makes possible a very fast,small circuit.

Central control unit 10 or central controller 11 contain suitableoperating or driving programs with which the travel and vibrationbehavior of the vibrating plate desired by the operator and specifiedvia operating elements (remote control, operating lever, buttons) can beconverted into control specifications for individual exciters 13. If,for example, the operator wishes to carry out a transition from standingcompaction of the vibrating plate to forward travel, central controlunit 10 or central controller 11 brings about an adjustment of the phaseposition in at least one of the individual exciters 13, causing a changein the direction of action of the resultant overall force.

For reliable normal operation, it is desirable for imbalance shafts 2 torotate with exactly the same rotational speed, as far as possible.Because, however, the position of imbalance shaft 2 is also constantlymonitored, deviations in the rotational speed can be corrected at anytime in order to maintain the desired phase position between theimbalance shafts. A progressive deviation of the rotational speed isthus excluded.

Hydraulic valve 6, which acts as an actuating element for controllingthe rotational speed and the phase position of imbalance shaft 2, shouldbe capable of being switched rapidly. In practice, various solutions arepossible in addition to, or also alternatively to, the specificembodiment shown in FIG. 1:

Hydraulic valve 6 can also be situated upstream in the line of supply tohydraulic motor 4. This valve should be a fast proportional valve. If amultiway valve is used, it is possible to rigidly clamp hydraulic motor4, so that for a certain period of time imbalance shaft 2 does notparticipate in the vibration production.

In addition, a plurality of hydraulic motors 4 can be supplied with thesame quantity of oil via a hydraulic synchronizing block. Alternatively,an individual hydraulic pump can be allocated to each hydraulic motor 4.The correction of the rotational speed and phase position of theimbalance shaft takes place with the aid of smaller, individuallyallocated metering or discharge valves that slightly increase ordecrease the volume flow of hydraulic fluid to or away from hydraulicmotor 4.

In addition, a proportional valve can be situated before the hydraulicsynchronizing block in order to adapt the rotational speed of theoverall system as needed in the particular circumstances. The hydraulicsynchronizing block can also be replaced by comparatively slowindividually provided metering valves.

In addition, it is possible to provide rapidly switched open/shutvalves, also in combination with one of the variants described above. Ifa plurality of rapid open/shut valves are connected in parallel, aproportionality can be reproduced in a stepped fashion.

Hydraulic motor 4 and hydraulic valve 6 can also be replaced by anadjusting hydraulic motor that can be controlled directly by controller8. In addition, an individually allocated adjusting hydraulic pump canbe provided for each imbalance shaft 2.

Due to the high vibration amplitudes at the lower mass, it is not usefulto situate electromagnetic valves there. These must always be providedon the upper mass. However, currently valves are being developed thatare more resistant to vibration, such as e.g. piezovalves or magneticfluid valves, which, if they prove successful in practice, could besituated very close to hydraulic motor 4. In this way, imprecisions dueto the compressibility of the hydraulic fluid and the elasticity of theconduits would be excluded.

FIG. 4 shows a schematic top view of a soil contact plate 12 on whichfour individual exciters 13 are situated at angles to one another.Through corresponding controlling of individual exciters 13, an almostarbitrary travel behavior of soil contact plate 12 can be achieved inthe forward, backward, and lateral directions, as well as rotation inplace and curved travel.

FIGS. 5 and 6 show additional specific embodiments of the presentinvention in the form of individual exciters 13 that are differentlysituated on soil contact plate 12. Individual exciters 13 are situatedin a star-shaped pattern (FIG. 5), axially (FIG. 5), in parallel (FIGS.5 and 6), or at an angle (FIGS. 4 to 6) to one another on the soilcontact plate.

In choosing the arrangement, almost any possibility is available tosomeone skilled in the art, because he no longer has to take intoaccount the mechanical coupling of the imbalance shafts of the vibrationexciter, as he previously had to do. Rather, he can situate theindividual exciters 13, each representing a complete unit, arbitrarilyon soil contact plate 12. There then remains only the problem ofprogramming the controlling, in the form of central control unit 10 orcentral controller 11, in a manner that suitably takes into account thearrangement of individual exciters 13.

FIG. 7 shows additional possibilities for the situation of individualexciters 13 on soil contact plate 12. For simplification, individualexciters 13 are shown only as lines.

FIG. 7 a correspondingly shows the imbalance shafts of individualexciters 13 situated partially in parallel, axially displaced,coaxially, and/or partially at an angle to, one another.

In addition to the “normal” individual exciters 13, FIG. 7 b showsreinforced individual exciters 14 that have an imbalance shaft having alarger imbalance mass. Correspondingly, reinforced individual exciters14 are symbolically shown not as lines, but rather as elongated boxes.

Reinforced individual exciters 14 can be used predominantly to achieve astronger compaction effect or a faster forward and backward travel.Correspondingly, the “normal” individual exciters 13, or the individualexciters having smaller imbalance masses, are provided for the steeringof the vibrating plate. The imbalance shafts provided in reinforcedindividual exciters 14, having enlarged imbalance masses, can however bereplaced by “normal” individual exciters 13 if for example a pluralityof individual exciters 13 are situated one after the other, parallel toone another.

FIG. 7 c symbolically shows a specific embodiment in which instead ofone soil contact plate 12, three partial soil contact plates 12 a, 12 b,12 c are provided, each bearing individual exciters 13, that areconnected to one another via connecting elements 15. In this way, arelatively large vibrating plate can be realized that nonethelesstravels easily over the ground due to the flexibility that can beachieved by the separate soil contact plates 12 a to 12 c, which arecapable of being moved relative to one another.

Central control unit 10 or central controller 11 make it possible toexecute prespecified programs, and thus to carry out defined travelstates. These include travel in a straight line forward and backward,vibration in place, or curved travel. Given more than four individualexciters 13 that can be controlled independently of one another, it isalso possible to adjust the movement of the lower mass by modifying theangular positions of the imbalance shafts to one another in such a waythat the impact of soil contact plate 12 on the soil takes place inparallel or as an intentional edge impact in which one edge, or evenonly a corner, first contacts the soil, while the rest of the undersideof soil contact plate 12 contacts the soil only after that. For centralcontrol unit 10 or central controller 11, intelligent control devicesusing fuzzy logic and/or having adaptive characteristics are preferredin order to enable adaptation to the actual soil and terrain conditions.

1. A vibrating plate for soil compaction, comprising: an upper masscomprising a drive; a lower mass comprising at least one soil contactplate; a vibration exciter device that generates vibrations in the soilcontact plate, the vibration exciter device having at least twoindividual exciters (13); wherein each of the individual exciters has aseparate, individually driven imbalance shaft that bears an imbalancemass; and wherein the individual exciters are capable of beingindividually controlled with respect to at least one of the rotationalspeed and the phase position of the respectively allocated imbalanceshaft.
 2. The vibrating plate as recited in claim 1, wherein each of theindividual exciters has a motor that rotationally drives the imbalanceshaft, and has a position sensor that acquires the position of theimbalance shaft in at least one position.
 3. The vibrating plate asrecited in claim 1, wherein a hydraulic valve is allocated to thehydraulic motor; and wherein the individual exciter has a controller forevaluating a signal from the position sensor and for controlling theactuating element in such a way as to achieve at least one of a targetrotational speed and a target phase position, prespecified to thecontroller, for the imbalance shaft.
 4. The vibrating plate as recitedin claim 1, wherein a central control unit is provided for coordinatingthe controllers of the individual exciters and for specifying at leastone of individual target rotational speed and a target phase positionfor each controller of the individual exciters, in such a way as toachieve a behavior of the soil contact plate that is at least one ofdesired by an operator and is specified by an operating or drivingprogram.
 5. The vibrating plate as recited in claim 1, wherein ahydraulic valve is allocated to the hydraulic motor; and a centralcontroller is provided for evaluating the signals from the positionsensors of the individual exciters and for individually controlling theactuating elements of the individual exciters in such a way as toachieve a behavior of the soil contact plate that is at least one ofdesired by an operator and is specified by an operating or drivingprogram.
 6. The vibrating plate as recited in claim 1, wherein theimbalance shafts of the individual exciters are driven with the samerotational speed.
 7. The vibrating plate as recited in claim 1, whereinthe imbalance shaft is driven by at least one of the individual exciterswith a different rotational speed than the imbalance shafts of the otherindividual exciters.
 8. The vibrating plate as recited in claim 7,wherein the other rotational speed is an odd-numbered multiple, inparticular three times or five times, of the rotational speed of theimbalance shafts of the other individual exciters.
 9. The vibratingplate as recited in claim 1, wherein at least one of the individualexciters is capable of being controlled in such a way that the imbalanceshaft allocated to it intentionally achieves a non-uniform rotationalspeed.
 10. The vibrating plate as recited in claim 1, wherein a secondvibration exciting device that generates vibrations in the soil contactplate is provided and has at least two imbalance shafts that arepositively coupled to one another and that are driven so as to rotate inopposite directions; wherein there is allocated to at least one of theimbalance shafts of the second vibration exciter device a positionsensor for determining the phase position of this imbalance shaft; andwherein a signal of the position sensor is supplied to at least one ofthe central control unit and the central controller in order tocoordinate at least one of the rotational speed and the phase positionof the imbalance shafts of the second vibration exciter device with theindividual exciters.
 11. The vibrating plate as recited in claim 1,wherein the position sensor has a device for acquiring the angle ofrotation.
 12. The vibrating plate as recited in claim 1, wherein atleast one of the individual exciters and the second vibration exciterdevice are situated in a distributed fashion on a plurality of soilcontact plates.
 13. The vibrating plate as recited in claim 1, whereinat least some of the imbalance shafts of the individual exciters aresituated on the soil contact plate in such a way that the force vectorsproduced by them act in different planes.
 14. The vibrating plate asrecited in claim 1, wherein at least some of the imbalance shafts of theindividual exciters are situated on the soil contact plate in one of astar-shaped pattern, axially, parallel, and at an angle to one another.15. The vibrating plate as recited in claim 1, wherein at least one ofthe imbalance shafts bears a larger imbalance mass than do otherimbalance shafts.